Haswell Review – It’s always exciting when a new CPU is launched, but never more than when Intel releases one as part of their “Tick Tock” development cadence.
If you don’t recall, it refers to their philosophy of releasing a new architecture one year, then refining that architecture with a smaller fab procuess. Last year’s release of Ivy Bridge was the “Tick” to Sandy Bridge’s “Tock”. In other words, the architecture was pretty much the same, but the process wasn’t. With Ivy Bridge, they nailed the 22nm process, and could then move onto developing the next architecture – Haswell. And that’s what we’re going to review today, in the form of the Core i7 4770K.
What’s New with Haswell?
Intel focused mainly on two things when developing Haswell: Power Efficiency, and iGPU performance. As you can guess, both those things lead to one main goal – usage in mobile as well as smaller all-in-one devices. Make no mistake, Intel is devoting most of their attention to prebuilt fully integrated systems. We already know they are leaving the desktop motherboard market, and that they are even developing a BGA version of the Core i7 desktop Haswell CPU. This is what got everyone up in arms about them abandoning us system builders all together. This ended up being untrue, which you’ll see soon.
As you’ll read if you are looking for coverage on the mobile side of things, Haswell has really improved power consumption, to the point where battery life has been extended more than any new Intel CPU ever. And I’m sure you’ve seen the numbers “75x” and “3x” thrown about when Haswell’s integrated GPU details were given. Those numbers only refer to the BGA (all in one) version by the way. Iris and Iris Pro will not be seen on the socketed CPUs we can buy today. At least not yet. Instead, we get HD 4600, an improved version of the HD 4000 IGP that was found on Ivy Bridge. We’ll get to that later in the review.
With such a narrow focus though, where does that leave us system builders and power users?
What About Us?
By focusing so strongly on power consumption and iGPU performance (on the BGA version only) you may first think that Intel has basically left us behind. After all, energy efficiency and overclocking don’t exactly go hand in hand. And if anything, overclocking has been getting harder and harder to do over new CPU releases.
Don’t worry, Intel’s got your back.
You may recall that I speculated back in January that we may see the return of BCLK overclocking with Haswell. This was based on different interviews and non-confidential presentations that were available at the time. Well it turns out I was right – BCLK overclocking has returned, and some other changes were made.
In fact, when first overclocking Haswell, you will probably need to acquaint yourself with some new settings. Different motherboards are sure to handle this differently; here’s how Intel’s main OC interface looks:
When overclocking Haswell, you have some new ratios to keep track of. Starting with BCLK or “Host Clock”, you can then set the ambiguous “Ring” clock. This is set via a standard multiplier, and cannot be set higher than the CPU core’s multiplier. Next is the CPU multiplier, something overclockers are already familiar with. Then you have the iGPU multiplier, which is X * BCLK*0.5. The problem here is that the 25x minimum iGPU multiplier will probably keep your potential BCLK speed low when using integrated graphics. As you can see here, with a BCLK of 125 MHz, the GPU runs at 1.56 GHz minimum. This is already quite a bit higher than its default speed of 1.2 GHz. Finally you have memory, which also gets its speed directly from BCLK. Several ratios are available to allow you to reach the speed you want.
Of course you could just set the core multiplier, and leave it at that. However raising the BCLK speed does overclock the rest of the CPU, which can lead to higher performance overall. It depends on what your goals are really. For everyday overclocking, start with finding out your top CPU speed, and go from there. That brings us to the bad news. If you were thinking that the return of BCLK overclocking would mean some form of overclocking on locked SKUs, I’m sorry to tell you that won’t be the case. Unfortunately it looks like the ability to change BCLK will only be available to unlocked “K Series” CPUs.
As for voltages, Intel gives you three different ways to handle those. By default, you can simply set the offset, which adds or subtracts to the voltage the CPU attempts to use on its own while under various loads. Next you have interpolative + offset. This allows the increased voltage to kick in under load, but remain stock at normal loads. Finally you have override + offset. With this, you can set an absolute static voltage that the CPU will use no matter what the load. This is the setting you’ll want to start out with at least, or when going for records.
Our Haswell Overclocking Results
We usually leave this to the end of the review, but there isn’t much else new to talk about with regards to what our readers care about most. We will touch on iGPU performance and power consumption later, but overclocking is by far the most interesting part of the desktop variant of Haswell.
We’re currently reviewing a Corsair H60 cooler, so that is what we used for this round of overclocking. Temperatures all stayed within the 80C threshold we’d want to stay under for day to day use. In fact I think we’ll find that the ‘soldering issues’ are most likely gone. Haswell runs quite a bit cooler than its 22nm cousin, Ivy Bridge. Throw enough voltage at it however, and it will start to cook.
Our early overclocking results, while not disappointing, will not blow your mind either. I think the type of setup we used here is typical of what most desktop overclockers would use. I didn’t want to throw too much voltage at it – 1.27v was as high as I ever took it. At default speeds, Haswell usually tops out at 1.0v or so under full load.
After an evening of overclocking, we were able to attain a stable 4.7 GHz overclock, with a voltage offset of +0.3v.
I usually disable Hyperthreading when overclocking, and this screenshot was taken while it was still disabled. Rest assured that it was still stable with HT on.
BCLK overclocking was also a success. In fact Intel’s own ‘quick overclock’ setting within the motherboard brought us here:
That’s right, no longer are you confined to 105 MHz or so BCLK. This overclock setting resides on the Intel motherboard we used for testing, and makes for a dead easy way to overclock to 4.6 GHz at the push of a button.
